Conventionally, inkjet printers performing inkjet printing have been widely used. One of inks widely used in inkjet printers is evaporation-drying (evaporation-drying and fixing) ink that fixes on a medium through evaporation of a solvent therein. More specifically, examples of evaporation-drying inks widely used include water-based pigment inks, latex inks, and solvent inks. In use of evaporation-drying ink, it is important to appropriately prevent bleeding of ink. One of conventionally known methods for preventing bleeding of evaporation-drying ink is to form an ink receiving layer on a medium. Another known method for preventing bleeding is to heat the medium, for example, with a print heater to heat the ink immediately after droplets land onto a medium.
Unfortunately, in the method of forming an ink receiving layer on a medium, it is necessary to use a special medium having an ink receiving layer formed in advance, causing a problem in that usable media are extremely limited. In addition, for example, there may be another problem in that strike-through occurs due to the solvent left after printing. Moreover, for example, when paper is used as a base layer on which an ink receiving layer is to be formed, using a large amount of ink for color printing may lead to bleeding, curling, or other problems. When a fabric medium such as cloth is used, the medium need to be coated with a preprocessing agent, such as a glue functioning as an ink receiving layer for preventing bleeding or an additive for assisting in color development of ink. In this case, for example, it is necessary to request the preprocessing of professionals, leading to a problem of time loss and cost increase. When heating is performed with a print heater or the like, ink is indirectly heated by heating a medium. In this configuration, excess heat is likely to cause adverse effects. More specifically, for example, heating the nozzle surface of the inkjet head with a heater tends to cause nozzle clogging or other problems. Such a problem is conspicuous, for example, particularly when the temperature for heating is increased in order to increase the printing speed.
In this respect, the inventor of the subject application has conceived of rapidly evaporating a solvent in ink by directly heating by ultraviolet radiation for evaporation-drying inks. The inventor has filed a patent application for such a configuration (for example, see PCT JP2017-004025). The configuration disclosed in Patent Literature 1, for example, can appropriately perform printing on a variety of media without forming an ink receiving layer. This configuration eliminates or reduces nozzle clogging because ink is directly heated, rather than indirectly heating by heating a medium.
Patent Literature 1: PCT JP2017-004025